Method and apparatus for avoiding failure of transmitting consecutive data packets

ABSTRACT

An apparatus includes a processor, and a non-transitory computer-readable storage medium coupled to the processor, and configured to store programmable instructions. When executed by the processor the programmable instructions cause the apparatus to maintain a transmission status of a previous data packet of a first access stratum entity, and adjust a transmission parameter of a current data packet, in response to the transmission status of the previous data packet being a transmission failure.

CROSS-REFERENCE TO RELATED DISCLOSURES

This application is a continuation of International Application No.PCT/CN2018/115330, filed on Nov. 14, 2018, which claims priority toChinese Patent Application No. 201711133111.X, filed on Nov. 15, 2017,the disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

Embodiments of this disclosure relate to the communications field, andmore specifically, to a method and an apparatus for avoiding failure oftransmitting consecutive data packets.

BACKGROUND

In an industrial control scenario, motion control is relativelychallenging due to a relatively high requirement on communication. Amotion controller is responsible for controlling and moving or rotatinga part (for example, a mechanical arm) of a machine to complete a task,for example, delivering goods or assembling parts. A communication modebetween the motion controller and the controlled part may be wiredcommunication or wireless communication. An advantage of the wirelesscommunication is that no line is deployed between the controller and thecontrolled part. This reduces costs, and increases support of a systemfor mobility, so that the controlled part can move anywhere. Inaddition, for some plant areas and factories, production lines arecustomized and reorganized based on requirements at any time. It is moreconvenient to reorganize a production line equipped with a wirelesscommunications system. As a 5G communications system develops,communication performance of the wireless communication becomes better,and is sufficient to meet a low-latency and high-reliabilitycommunications requirement in the industrial control scenario.Therefore, 5G communication will be one of main communicationstechnologies in the future industrial control field.

In the industrial control scenario, a requirement on a communicationsindicator is relatively high, and control signaling is transmitted withhigh reliability assurance in short time. In the control scenario, thecontroller usually transmits an instruction to the controlled unitperiodically, to instruct the controlled unit how to perform an action.Because 100% reliability cannot be achieved for communication, when anapplication layer is designed, an error is usually allowed to occur inone instruction, but errors are not allowed to occur in two consecutiveinstructions. If two pieces of consecutive control signaling are lost ortransmitted incorrectly, the application layer performs consecutiveactions according to incorrect instructions or disconnects a connection.This may cause device damage or production line stoppage, resulting inhuge property loss or personal safety accidents.

SUMMARY

Embodiments of this disclosure provide a method and an apparatus foravoiding failure of transmitting consecutive data packets, to ensurethat in a data transmission process, a case in which two consecutiveapplication layer data packets both fail to be transmitted does notoccur. This improves data transmission reliability.

According to some embodiments, a method for avoiding failure oftransmitting consecutive data packet is provided. The method includes:

maintaining, by a first access stratum entity of a transmit end, atransmission status of a previous data packet of the first accessstratum entity; and if the transmission status of the previous datapacket is transmission failure, adjusting, by the transmit end, atransmission parameter of a current data packet.

In a possible implementation, the first access stratum entity of thetransmit end is one of the following: a radio link control layer; aservice data adaptation protocol layer; a radio resource control layer;a media access control layer; or a physical layer.

In some embodiments, the data packet is a service data unit or aprotocol data unit.

In a possible implementation, the access stratum entity of the transmitend maintains the transmission status of the previous data packet of theaccess stratum entity based on at least one of the followinginformation: when a timer maintained by the first access stratum entityof the transmit end expires and the previous data packet is still nottransmitted successfully, it is considered that the transmission statusof the previous data packet is transmission failure; or the previousdata packet is transmitted successfully before a timer maintained by thefirst access stratum entity of the transmit end expires, it isconsidered that the transmission status of the previous data packet istransmission success; indication information sent by a first accessstratum entity of a receive end to an access stratum of the transmit endis used to indicate that the previous data packet of the first accessstratum entity of the transmit end is transmitted successfully or failsto be transmitted; indication information sent by a second accessstratum entity of the transmit end to the first access stratum entity ofthe transmit end is used to indicate that the previous data packet ofthe first access stratum entity of the transmit end is transmittedsuccessfully or fails to be transmitted; indication information sent bya second access stratum entity of a receive end to an access stratum ofthe transmit end is used to indicate that the previous data packet ofthe first access stratum entity of the transmit end is transmittedsuccessfully or fails to be transmitted; the first access stratum entityor a second access stratum entity of the transmit end determines, basedon a sequence number of the current data packet, that the previous datapacket fails to be transmitted if the sequence number of the receivedcurrent data packet and the sequence number of the previous data packetare not consecutive; the first access stratum entity or a second accessstratum entity of the transmit end learns of a period of a data packetbased on QoS information, and if no data packet is received within aprevious period, determines that the previous data packet fails to betransmitted; or indication information sent by a non-access stratum oran application layer of the transmit end to an access stratum of thetransmit end is used to indicate that the previous data packet of thefirst access stratum entity of the transmit end is transmittedsuccessfully or fails to be transmitted.

In some embodiments, the transmission parameter includes at least one ofthe following: a modulation and coding scheme; a maximum quantity oftransmissions of a hybrid automatic repeat request HARQ; a maximumquantity of transmissions of an automatic repeat request ARQ; a periodof a transmission resource; a location of a transmission resource; asize of a transmission resource; a type of a transmission resource; apriority of a logical channel; a priority of a radio bearer; atransmission mode of radio link control; a quantity of transmittedcarriers; a type of a radio bearer; or a function of a radio bearer.

According to some embodiments, an embodiment of this disclosure providesan apparatus for avoiding failure of transmitting consecutive datapackets, configured to perform the method according to the embodiments.Specifically, the apparatus for avoiding failure of transmittingconsecutive data packets includes a unit configured to perform themethod according to any one of the embodiments and the implementationsof the embodiments.

According to some embodiments, a computer-readable storage medium isprovided. The computer-readable storage medium stores a computer program(an instruction), and when the program (the instruction) runs on acomputer, the computer is enabled to perform the method according to anyone of the foregoing embodiments.

According to some embodiments, this disclosure provides a chip system.The chip system includes a processor, configured to support an apparatusfor avoiding failure of transmitting consecutive data packets inimplementing a function in the foregoing aspects, for example,generating or processing data and/or information in the foregoingmethod. In a possible design, the chip system further includes a memory.The memory is configured to store a program instruction and data thatare used for the apparatus for avoiding failure of transmittingconsecutive data packets. The chip system may include a chip, or mayinclude a chip and another discrete device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic architectural diagram of a wireless communicationssystem according to some embodiments of this disclosure;

FIG. 2 is a structural diagram of a terminal device according to someembodiments of this disclosure;

FIG. 3 is a structural diagram of an access network device according tosome embodiments of this disclosure;

FIG. 4 is a schematic flowchart of a method for avoiding failure oftransmitting consecutive data packets according to some embodiments ofthis disclosure;

FIG. 5 is a schematic diagram of transmission of a data packet accordingto some embodiments of this disclosure;

FIG. 6 is a schematic flowchart of a method for avoiding failure oftransmitting consecutive data packets according to some embodiments ofthis disclosure;

FIG. 7 is a schematic flowchart of adjustment performed based on an RLCSDU transmission status error fed back by an RLC layer of a receive endaccording to some embodiments of this disclosure;

FIG. 8 is a schematic flowchart of adjustment performed based on an RLCSDU transmission status error fed back by a MAC layer of a receive endaccording to some embodiments of this disclosure;

FIG. 9 is a schematic flowchart of adjustment performed based on a PDCPSDU transmission status error fed back by a PDCP layer of a receive endaccording to some embodiments of this disclosure;

FIG. 10 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to some embodimentsof this disclosure;

FIG. 11 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to some embodimentsof this disclosure;

FIG. 12 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to some embodimentsof this disclosure;

FIG. 13 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to some embodimentsof this disclosure; and

FIG. 14 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to some embodimentsof this disclosure.

DETAILED DESCRIPTION

To make a person skilled in the art understand the solutions in thepresent disclosure better, the following describes several embodimentsin more detail with reference to the accompanying drawings andimplementations. Apparently, the described embodiments are some ratherthan all of the embodiments of the present disclosure. All otherembodiments obtained by a person of ordinary skill in the art based onthe embodiments of the present disclosure without creative efforts shallfall within the protection scope of the present disclosure. Thefollowing describes the technical solutions in embodiments of thisdisclosure with reference to the accompanying drawings in theembodiments of this disclosure. It should be noted that the technicalsolutions and features in the embodiments of this disclosure may bemutually combined in a case of no conflict.

In the embodiments of this disclosure, “a/an” means a single individual,and does not indicate that “a/an” can only be one individual and cannotbe applied to another individual. For example, in the embodiments ofthis disclosure, “a terminal device” refers to a particular terminaldevice, and this does not mean that “a terminal device” can be appliedonly to one particular terminal device. The terms “system” and “network”may be used interchangeably in this disclosure.

A reference to “an embodiment” (or “an implementation”) or “embodiments”(or “implementations”) in this disclosure means that a specific feature,a structure, a feature, and the like that are described with theembodiments are included in at least one embodiment. Therefore, “in anembodiment” or “in the embodiments” that appears throughout thisspecification does not represent a same embodiment.

Further, in the embodiments of this disclosure, the terms “and/or” and“at least one” used in cases of “A and/or B” and “at least one of A andB” include any one of three scenarios: a scenario in which A is includedbut B is excluded, a scenario in which B is included but A is excluded,and a scenario in which both options A and B are included. In anotherexample, in a case of “A, B, and/or C” and “at least one of A, B, and/orC”, this phrase includes any one of six scenarios: a scenario in which Ais included but both B and C are excluded, a scenario in which B isincluded but both A and C are excluded, a scenario in which C isincluded but both A and B are excluded, a scenario in which both A and Bare included but C is excluded, a scenario in which both B and C areincluded but A is excluded, a scenario in which both A and C areincluded but B is excluded, and a scenario in which three options A, B,and C are included. As easily understood by a person of ordinary skillin the art and a related art, all other similar descriptions can beunderstood in the foregoing manner in the embodiments of thisdisclosure.

FIG. 1 is a schematic diagram of communication between a wireless deviceand a wireless communications system. The wireless communications systemmay be a system to which various radio access technologies (RAT) areapplied, for example, code division multiple access (CDMA), timedivision multiple access (TDMA), and frequency division multiple access(FDMA), orthogonal frequency-division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and anothersystem. For example, the wireless communications system may be a longterm evolution (LTE) system, a CDMA system, a wideband code divisionmultiple access (WCDMA) system, a global system for mobilecommunications (GSM) system, a wireless local area network (WLAN)system, a new radio (NR) system, various evolved or converged systems,and a system using a future communications technology. The systemarchitecture and the service scenario described in the embodiments ofthis disclosure are intended to describe the technical solutions in theembodiments of this disclosure more clearly, and do not constitute alimitation on the technical solutions provided in the embodiments ofthis disclosure. A person of ordinary skill in the art may know that,with evolution of a network architecture and emergence of a new servicescenario, the technical solutions provided in the embodiments of thisdisclosure are also applicable to similar technical problems.

For brevity, FIG. 1 shows communication between one network device 102(for example, an access network device) and two wireless devices 104(for example, terminal devices). Generally, the wireless communicationssystem may include any quantities of network devices and terminaldevices. The wireless communications system may further include one ormore core network devices, a device configured to bear a virtualizednetwork function, or the like. The access network device 102 may providea service for the wireless device by using one or more carriers. In thisdisclosure, the access network device and the terminal device arefurther collectively referred to as wireless apparatuses.

In this disclosure, the access network device 102 is an apparatus thatis deployed in a radio access network to provide a wirelesscommunication function for a terminal device. The access network devicemay include a macro base station (BS), a micro base station (alsoreferred to as a small cell), a relay node, an access point, or the likein various forms. In systems that use different radio accesstechnologies, names of a device having a radio access function may bedifferent. For example, in an LTE system, the device is referred to asan evolved NodeB (eNB or eNodeB); in a 3rd generation (3G) system, thedevice is referred to as a NodeB (Node B), and the like. For ease ofdescription, in this disclosure, the device is briefly referred to as anaccess network device, and is sometimes referred to as a base station.

The wireless device in the embodiments of this disclosure may includevarious handheld devices, vehicle-mounted devices, wearable devices, orcomputing devices that have a wireless communication function, oranother processing device connected to a wireless modem. The wirelessdevice may be referred to as a terminal device, or may be referred to asa mobile station (MS), a terminal, user equipment (UE), or the like. Thewireless device may be a subscriber unit, a cellular phone, asmartphone, a wireless data card, a personal digital assistant (PDA)computer, a tablet computer, a modem or a modem processor, a handhelddevice, a laptop computer, a netbook, a cordless phone, or a wirelesslocal loop (WLL) station, a Bluetooth device, a machine typecommunication (MTC) terminal, and the like. For ease of description, thewireless device is briefly referred to as a terminal device or UE inthis disclosure.

The wireless device may support one or more wireless technologies usedfor wireless communication, for example, 5G, LTE, WCDMA, CDMA, lx, timedivision-synchronous code division multiple access (TS-SCDMA), GSM,802.11, and the like. The wireless device may also support a carrieraggregation technology.

A plurality of wireless devices may perform a same service or differentservices, for example, a mobile broadband service, an enhanced mobilebroadband (eMBB) service, and an ultra-reliable low-latencycommunication (URLLC) service.

Further, a possible schematic structural diagram of the access networkdevice 102 may be shown in FIG. 2. The access network device 102 canperform a method provided in the embodiments of this disclosure. Theaccess network device 102 may include a controller or a processor 201(the processor 201 is used as an example below for description) and atransceiver 202. The controller/processor 201 is sometimes also referredto as a modem processor. The modem processor 201 may include a basebandprocessor (BBP) (not shown). The baseband processor processes a receiveddigitalized signal, to extract information or a data bit transmitted inthe signal. Therefore, based on a requirement or an expectation, the BBPis usually implemented in one or more digital signal processors (DSP) inthe modem processor 201 or implemented as a separated integrated circuit(IC).

The transceiver 202 may be configured to: support information receivingand sending between the access network device 102 and the terminaldevices, and support radio communication between the terminal devices.The processor 201 may be further configured to perform various functionsfor communication between the terminal devices and another networkdevice. On an uplink, an uplink signal from the terminal device isreceived by using an antenna, demodulated by the transceiver 202, andfurther processed by the processor 201, to restore service data and/orsignaling information sent by the terminal device. On a downlink,service data and/or a signaling message are/is processed by the terminaldevice, modulated by the transceiver 202 to generate a downlink signal,and transmitted to UE by using an antenna. The access network device 102may further include a memory 203, which may be configured to storeprogram code and/or data of the access network device 102. Thetransceiver 202 may include an independent receiver circuit and anindependent transmitter circuit, or maybe a circuit implementingreceiving and sending functions. The access network device 102 mayfurther include a communications unit 204, configured to supportcommunication between the access network device 102 and another networkentity. For example, the communications unit 204 is configured tosupport communication between the access network device 102 and anetwork device of a core network.

In some embodiments, the access network device may further include abus. The transceiver 202, the memory 203, and the communications unit204 may be connected to the processor 201 by using the bus. For example,the bus may be a peripheral component interconnect (PCI) bus, anextended industry standard architecture (EISA) bus, or the like. The busmay include an address bus, a data bus, a control bus, and the like.

FIG. 3 is a possible schematic structural diagram of a terminal devicein the foregoing wireless communications system. The terminal device canperform a method provided in the embodiments of this disclosure. Theterminal device may be either of the two terminal devices 104. Theterminal device includes a transceiver 301, an application processor(application processor) 302, a memory 303, and a modem processor (modemprocessor) 304.

The transceiver 301 may adjust (for example, perform analog conversion,filtering, amplification, and up-conversion on) an output sample andgenerate an uplink signal. The uplink signal is transmitted to the basestation in the foregoing embodiment by using an antenna. On a downlink,the antenna receives a downlink signal transmitted by an access networkdevice. The transceiver 301 may adjust (for example, perform filtering,amplification, down-conversion, and digitalization on) a signal receivedfrom the antenna and provide an input sample.

The modem processor 304 is sometimes also referred to as a controller ora processor, and may include a baseband processor (BBP) (not shown). Thebaseband processor processes a received digitalized signal, to extractinformation or a data bit transmitted in the signal. Based on arequirement or an expectation, the BBP is usually implemented in one ormore digits in the modem processor 304 or implemented as a separatedintegrated circuit (IC).

In a design, the modem processor 304 may include an encoder 3041, amodulator 3042, a decoder 3043, and a demodulator 3044. The encoder 3041is configured to encode a to-be-sent signal. For example, the encoder3041 may be configured to: receive service data and/or a signalingmessage that are/is to be sent on an uplink, and perform processing (forexample, formatting, encoding, or interleaving) on the service data andthe signaling message. The modulator 3042 is configured to modulate anoutput signal of the encoder 3041. For example, the modulator mayperform processing such as symbol mapping and/or modulation on theoutput signal (data and/or signaling) of the encoder, and provide anoutput sample. The demodulator 3044 is configured to demodulate an inputsignal. For example, the demodulator 3044 processes an input sample andprovides symbol estimation. The decoder 3043 is configured to decode ademodulated input signal. For example, the decoder 3043 performsprocessing such as de-interleaving and/or decoding on the demodulatedinput signal, and outputs a decoded signal (data and/or signaling). Theencoder 3041, the modulator 3042, the demodulator 3044, and the decoder3043 may be implemented by the integrated modem processor 304. Theseunits perform processing based on a radio access technology used in aradio access network.

The modem processor 304 receives, from the application processor 302,digitalized data that may represent voice, data, or control information,and processes the digitalized data for transmission. The modem processormay support one or more of a plurality of wireless communicationprotocols of a plurality of communications systems, for example, LTE,new radio, a universal mobile telecommunications system (UMTS), and highspeed packet access (HSPA). In some embodiments, the modem processor 304may also include one or more memories.

In some embodiments, the modem processor 304 and the applicationprocessor 302 may be integrated in one processor chip. The memory 303 isconfigured to store program code (sometimes also referred to as aprogram, an instruction, software, or the like) and/or data that are/isused to support communication of the terminal device.

It should be noted that, the memory 203 or the memory 303 may includeone or more storage units, for example, may be a storage unit that is inthe processor 201 or the modem processor 304 or the applicationprocessor 302 and that is used to store program code, or may be anexternal storage unit independent of the processor 201 or the modemprocessor 304 or the application processor 302, or may be a componentincluding a storage unit that is in the processor 201 or the modemprocessor 304 or the application processor 302 and an external storageunit that is independent of the processor 201 or the modem processor 304or the application processor 302.

The processor 201 and the modem processor 304 may be processors of asame type, or may be processors of different types. For example, theprocessor 201 and modem processor 304 each may be implemented as acentral processing unit (CPU), a general-purpose processor, a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), a field programmable gate array (FPGA) or another programmablelogic device, a transistor logic device, a hardware component, anotherintegrated circuit, or any combination thereof. The processor 201 andthe modem processor 304 may implement or execute various examples oflogic blocks, modules, and circuits described with reference to contentdisclosed in the embodiments of this disclosure. The processor mayalternatively be a combination that implements a computing functiondevice, for example, a combination including one or moremicroprocessors, a combination of a DSP and a microprocessor, or asystem-on-a-chip (SOC).

A person skilled in the art can understand that various explanatorylogic blocks, modules, circuits, and algorithms described with referenceto the various aspects disclosed in this disclosure may be implementedas electronic hardware, an instruction that is stored in a memory oranother computer-readable medium and that is executed by a processor oranother processing device, or a combination thereof. As an example, thedevices described in this specification may be applied to any circuit,hardware component, IC, or IC chip. The memory disclosed in thisdisclosure may be any type of memory in any size, and may be configuredto store any type of information. To clearly explain suchinterchangeability, various explanatory components, blocks, modules,circuits, and steps have been generally described above based onfunctionality. How to implement such functionality depends on a specificapplication, a design selection, and/or a design constraint that isimposed on an entire system. A person skilled in the art may usedifferent manners to implement the described functions for eachparticular application, but it should not be considered that suchimplementation goes beyond the scope of this disclosure.

In a design process of an existing communications technology including a5G technology, transmission reliability of consecutive application layerdata packets is not specially considered. In some approaches,transmission reliability assurance is usually designed for only one datapacket, and transmission reliability of the data packet is ensured tosome extent by using a retransmission mechanism. In the embodiments ofthis disclosure, for a feature that an application layer does not allowerrors of two consecutive data packets, a method for dynamicallyadjusting transmission reliability of a data packet based on atransmission status of a previous data packet is provided. The followingdescribes in more details the solutions provided in the embodiments ofthis disclosure with reference to the accompanying drawings.

FIG. 4 is a schematic flowchart of a method for avoiding failure oftransmitting consecutive data packets according to an embodiment of thisdisclosure. The method may be applied to the network architecture shownin FIG. 1, and the terminal device and the access network device thatare shown in FIG. 2 and FIG. 3. It should be noted that a transmit endin this embodiment of this disclosure may be a terminal device or anaccess network device. When the transmit end is a terminal device, areceive end may be an access network device. When the transmit end is anaccess network device, the receive end may be a terminal device.However, this disclosure is not limited thereto.

Step 401: A first access stratum entity of the transmit end maintains atransmission status of a previous data packet of the first accessstratum entity.

The data packet herein may be a service data unit (SDU) or a protocoldata unit (PDU) of the first access stratum entity.

In some embodiments, the data packet is an application layer datapacket, and is used, at a communications layer, as an initial servicedata unit (SDU) of the communications layer. The transmission statusincludes “transmission success” or “transmission failure”.

In some embodiments, the first access stratum entity of the transmit endmay be at least one of the following: a service data adaptation protocol(SDAP) layer, a packet data convergence protocol (PDCP) layer, a radiolink control (RLC) layer, a media access control (MAC) layer, a radioresource control (RRC) layer, or a physical (PHY) layer.

FIG. 5 is used as an example. For example, the application layer datapacket is transmitted as an SDAP SDU, and is encapsulated into an SDAPPDU after an SDAP header is added to the SDAP SDU, and the SDAP PDU isdelivered to the PDCP layer. The SDAP PDU received at the PDCP layer istransmitted as a PDCP SDU, and is encapsulated into a PDCP protocol dataunit (PDU) after a PDCP header is added to the PDCP SDU, and the PDCPPDU is delivered to a lower layer, RLC layer. The PDCP PDU received atthe RLC layer is an RLC SDU. The RLC SDU is encapsulated into an RLC PDUafter an RLC header is added to the RLC SDU. The RLC layer has asegmentation function. Therefore, one RLC SDU may be segmented into aplurality of RLC PDUs for transmission. RLC PDUs of a plurality oflogical channels are multiplexed at the MAC layer, to form a MAC PDU.Each RLC PDU is considered as a MAC SDU at the MAC layer.

In some embodiments, the access stratum entity of the transmit endmaintains the transmission status of the previous data packet of theaccess stratum entity based on at least one of the followinginformation:

when a timer maintained by the first access stratum entity of thetransmit end expires and the previous data packet is still nottransmitted successfully, it is considered that the transmission statusof the previous data packet is transmission failure; or the previousdata packet is transmitted successfully before a timer maintained by thefirst access stratum entity of the transmit end expires, it isconsidered that the transmission status of the previous data packet istransmission success;

indication information sent by a first access stratum entity of areceive end to an access stratum of the transmit end is used to indicatethat the previous data packet of the first access stratum entity of thetransmit end is transmitted successfully or fails to be transmitted;

indication information sent by a second access stratum entity of thetransmit end to the first access stratum entity of the transmit end isused to indicate that the previous data packet of the first accessstratum entity of the transmit end is transmitted successfully or failsto be transmitted;

indication information sent by a second access stratum entity of areceive end to an access stratum of the transmit end is used to indicatethat the previous data packet of the first access stratum entity of thetransmit end is transmitted successfully or fails to be transmitted;

the first access stratum entity or a second access stratum entity of thetransmit end determines, based on a sequence number of the current datapacket, that the previous data packet fails to be transmitted if thesequence number of the received current data packet and the sequencenumber of the previous data packet are not consecutive;

the first access stratum entity or a second access stratum entity of thetransmit end learns of a period of a data packet based on QoSinformation, and if no data packet is received within a previous period,determines that the previous data packet fails to be transmitted; or

indication information sent by a non-access stratum or an applicationlayer of the transmit end to an access stratum of the transmit end isused to indicate that the previous data packet of the first accessstratum entity of the transmit end is transmitted successfully or failsto be transmitted.

It should be noted that the first access stratum entity and the secondaccess stratum entity in this embodiment of this disclosure may be anon-access stratum entity or another protocol layer entity. This is notlimited in this disclosure.

Step 402: If the transmission status of the previous data packet istransmission failure, the transmit end adjusts a transmission parameterof a current data packet. The transmission parameter may be a radioresource configuration parameter.

In some embodiments, the transmission parameter includes at least one ofthe following: a modulation and coding scheme (MCS); a maximum quantityof transmissions of a hybrid automatic repeat request (HARQ); a maximumquantity of transmissions of an automatic repeat request (ARQ); a periodof a transmission resource; a location of a transmission resource; asize of a transmission resource; a type of a transmission resource; apriority of a logical channel; a priority of a radio bearer; atransmission mode (an RLC AM or UM or TM) of radio link control; aquantity of transmitted carriers; a type of a radio bearer; a functionof a radio bearer (for example, use of repeat transmission or not, oruse of single connectivity, dual connectivity, or multi-connectivity);or transmit power.

An MCS modulation and coding table is a representation form proposed in802.11n to represent a communication rate. The MCS uses a factor thataffects the communication rate as a column of the table, and uses an MCSindex as a row to form a rate table. Therefore, each MCS indexcorresponds to a physical transmission rate under a group of parameters.

The maximum quantity of transmissions of the hybrid automatic repeatrequest indicates a maximum quantity of transmissions of a same MAC PDUat the MAC layer.

The maximum quantity of transmissions of the automatic repeat requestindicates a maximum quantity of transmissions of a same RLC PDU at theRLC layer.

The period of the transmission resource may include, for example, aperiod of an semi-persistent scheduling (SPS) resource, namely, aninterval between two neighboring SPS resources in time domain. Forexample, an original SPS period is 2, and an SPS period of a subsequentdata packet is 1.

The location of the transmission resource may include, for example, astart location and an end location of the SPS resource in the timedomain, and a start location and an end location of the SPS resource infrequency domain. Specifically, a frequency domain location may be acarrier index, a subcarrier index, or a bandwidth part (BWP) index, anda time domain location may be a symbol index, a slot number, a subframenumber, a frame number, a superframe number, or the like.

The size of the transmission resource may include a size of the SPSresource, a quantity of time domain units occupied in the time domain,or a quantity of frequency domain units occupied in time domain.Specifically, the time domain unit may be a symbol, a slot, a subframe,a frame, a superframe, or the like. The frequency domain unit may be acarrier, a subcarrier, a BWP, or the like.

The type of the transmission resource may include, for example, an SPSresource, a grant-free resource, or a dynamic scheduling resource.

The priority of the logical channel is used to indicate a priority ofeach logical channel when the logical channel is multiplexed at the MAClayer. Different logical channels may have a same priority.

The radio link control layer, the RLC layer, has three transmissionmodes: an RLC AM, an RLC UM, and an RLC TM.

RLC acknowledged mode (AM): A reliable transmission service is providedthrough error detection and retransmission. This mode provides all RLCfunctions.

RLC unacknowledged mode (UM): This mode provides all RLC functionsexcept retransmission and re-segmentation. Therefore, this mode providesan unreliable transmission service.

RLC transparent mode (TM): In this mode, the RLC can be considered asnull. No processing is performed on the RLC SDU, and no RLC header isadded. This is because only a data passthrough function is provided inthis mode.

The type of the radio bearer includes a data radio bearer (DRB) and asignaling radio bearer (SRB). Further, the type of the radio bearer mayfurther include different DRB IDs and different SRB IDs.

The transmit power is transmit power used by the transmit end totransmit a MAC PDU.

FIG. 6 is a schematic flowchart of a method for avoiding failure oftransmitting consecutive data packets according to an embodiment of thisdisclosure. The method may be applied to the network architecture shownin FIG. 1, and the terminal device and the access network device thatare shown in FIG. 2 and FIG. 3. It should be noted that a transmit endin this embodiment of this disclosure may be a terminal device or anaccess network device. When the transmit end is a terminal device, areceive end may be an access network device. When the transmit end is anaccess network device, the receive end may be a terminal device.However, this disclosure is not limited thereto.

Step 601: A first access stratum entity of the transmit end obtainstransmission statuses of previous n data packets of the first accessstratum entity.

The data packet herein may be a service data unit (SDU) or a protocoldata unit (PDU) of the first access stratum entity. The data packet maybe specifically a data packet from an application layer, and is used, ata communications layer, as an initial service data unit (SDU) of thecommunications layer. The transmission status includes transmissionsuccess or transmission failure.

In some embodiments, the first access stratum entity of the transmit endmay be at least one of the following: a service data adaptation protocol(SDAP) layer, a packet data convergence protocol (PDCP) layer, a radiolink control (RLC) layer, a media access control (MAC) layer, a radioresource control (RRC) layer, or a physical (PHY) layer.

Step 602: If there are m data packets whose transmission statuses aretransmission failure in the previous n data packets, the transmit endadjusts a transmission parameter of a current data packet.

The transmission parameter in step 602 is the same as the transmissionparameter in step 402, and details are not described herein again.

It should be noted that, after obtaining the transmission statuses ofthe previous n data packets of the first access stratum entity, thefirst access stratum entity of the transmit end determines whether thereare m data packets whose transmission statuses are transmission failurein the previous n data packets, where n is a positive integer, and m isa positive integer less than or equal to n. The m data packets may beconsecutive data packets, or may be inconsecutive data packets. When them data packets are consecutive data packets, 2. If the transmit enddetermines that there are m data packets whose transmission statuses aretransmission failure in the previous n data packets, the transmit endadjusts the transmission parameter of the current data packet (an(n+1)^(th) data packet).

In some embodiments, the access stratum entity of the transmit endobtains the transmission statuses of the previous n data packets of theaccess stratum entity based on at least one of the following:

(1) The first access stratum entity of the transmit end maintains aplurality of counters (for example, a first counter and a secondcounter). The first counter is used to collect statistics on the n datapackets of the first access stratum entity, and the second counter isconfigured to collect statistics on an accumulated quantity of datapackets that fail to be transmitted in the n data packets. In animplementation of this disclosure, initial values of the first counterand the second counter are both 0. A threshold is set for the secondcounter. The threshold may be configured by a core network device or theaccess network device, or the threshold may be obtained from anapplication layer or a non-access stratum of the terminal device. Thefirst access stratum entity of the transmit end obtains the transmissionstatus of each data packet. An obtaining method is the same as themethod for obtaining the transmission status of the previous data packetin step 401, and is not described herein again. The value of the firstcounter is increased by 1 each time a data packet of the first accessstratum entity is obtained. When a transmission status of a data packetobtained by the first access stratums entity of the transmit end istransmission failure, the value of the second counter is increased by 1.When the value of the second counter is greater than or equal to thethreshold, for example, the threshold is set to m, it is considered thatthere are m data packets whose transmission statuses are transmissionfailure in the previous n data packets of the first access stratumentity of the transmit end, and the transmit end adjusts thetransmission parameter of the current data packet. When the value of thefirst counter is equal to n, and the value of the second counter is lessthan the threshold m, the transmit end still maintains the transmissionparameter of the current data packet.

(2) Indication information sent by a first access stratum entity of areceive end to an access stratum of the transmit end is used to indicatewhether there are m data packets that fail to be transmitted in theprevious n data packets of the first access stratum entity of thetransmit end.

(3) Indication information sent by a second access stratum entity of thetransmit end to the first access stratum entity of the transmit end isused to indicate whether there are m data packets that fail to betransmitted in the previous n data packets of the first access stratumentity of the transmit end.

(4) Indication information sent by a second access stratum entity of areceive end to an access stratum of the transmit end is used to indicatewhether there are m data packets that fail to be transmitted in theprevious n data packets of the first access stratum entity of thetransmit end.

(5) The first access stratum entity of a second access stratum entity ofthe transmit end may receive indication information of a first accessstratum entity of a receive end or indication information of a secondaccess stratum entity of the transmit end. The indication informationincludes sequence numbers of currently transmitted data packets and atransmission status of a data packet corresponding to each sequencenumber. The first access stratum entity of the transmit end maintains acounter, and the counter is configured to collect statistics on anaccumulated quantity of data packets that fail to be transmitted. Aninitial value of the counter is 0. If the sequence number of the currentreceived data packet and the sequence number of a previous data packetare not consecutive, the value of the counter is increased by 1. In anembodiment of this disclosure, a threshold of the counter is set to m.When the value of the counter is greater than or equal to the thresholdm, it is considered that there are m data packets whose transmissionstatuses are transmission failure in the previous n data packets of theaccess stratum entity of the transmit end.

(6) Indication information sent by a non-access stratum or anapplication layer of the transmit end to an access stratum of thetransmit end is used to indicate whether there are m data packets thatfail to be transmitted in the previous n data packets of the firstaccess stratum entity of the transmit end.

It should be noted that the first access stratum entity and the secondaccess stratum entity in this embodiment of this disclosure may be anon-access stratum entity or another protocol layer entity. This is notlimited in this disclosure.

In some embodiments, when the transmit end is a terminal device, n maybe configured by an access network device or a core network device; or nmay be obtained from an application layer or a non-access stratum of theterminal device.

In an embodiment of this disclosure, when the transmit end is theterminal device, n may be obtained through calculation based on asurvival time (survival time) T of the application layer and a cycletime (cycle time or transfer time) t of an application layer service(service). For example, n=T/t. If T cannot be exactly divided by t, aresult may be rounded up or down. T and t are configured by the accessnetwork device or the core network device, or are obtained from theapplication layer or the non-access stratum of the terminal device. Inthis case, m may be configured by the access network device or the corenetwork device, or may be obtained from the application layer or thenon-access stratum of the terminal device.

In some embodiments, when the transmit end is an access network device,n may be configured by a core network device or reported by a terminaldevice.

In another embodiment of this disclosure, when the transmit end is theaccess network device, n may also be obtained through calculation basedon a survival time T of an application layer and a cycle time t of anapplication layer service. For example, n=T/t. Similarly, if T cannot beexactly divided by t, a result may be rounded up or down. T and t areconfigured by the core network device or reported by the terminaldevice. In this case, m may be configured by the core network device orreported by the terminal device.

In another embodiment of this disclosure, m may also be obtained throughcalculation based on a survival time T of an application layer and acycle time t of an application layer service. For example, m=T/t.Similarly, if T cannot be exactly divided by t, a result may be roundedup or down. T and t are configured by a core network device or reportedby a terminal device. In this case, n may be configured by the corenetwork device or configured by an access network device, or reported bythe terminal device, or obtained from an application layer or anon-access stratum of the terminal device.

It should be noted that the embodiments of this disclosure are notlimited to the embodiment described in FIG. 6. For example, according tothe method provided in the embodiments of this disclosure, the firstaccess stratum entity of the transmit end may obtain a transmissionstatus of each data packet of the first access stratum entity. Withinpreset time, when there are s data packets whose transmission statusesare transmission failure in the obtained data packets of the firstaccess stratum entity, the transmit end adjusts the transmissionparameter of the current data packet. s is a positive integer.

For another example, according to the method provided in the embodimentsof this disclosure, the first access stratum entity of the transmit endmay obtain transmission statuses of at least k data packets that are ofthe first access stratum entity and that are counted backward. Whenthere are k consecutive data packets whose transmission statuses aretransmission failure in the obtained data packets of the first accessstratum entity, the transmit end adjusts the transmission parameter ofthe current data packet. k is a positive integer, and k≥2.

In some embodiments, k may be 2, 3, or 4. In other words, when there are2, 3, or 4 consecutive data packets whose transmission statuses aretransmission failure in the obtained data packets of the first accessstratum entity, the transmit end adjusts the transmission parameter ofthe current data packet. To be specific, when k=2, the transmit endadjusts the transmission parameter of the current third data packet;when k=3, the transmit end adjusts the transmission parameter of thecurrent fourth data packet; when k=4, the transmit end adjusts thetransmission parameter of the current fifth data packet.

For another example, according to the method provided in the embodimentsof this disclosure, the first access stratum entity of the transmit endobtains transmission statuses of at least previous x data packets of theaccess stratum entity. When the obtained transmission statuses of theprevious x data packets are transmission failure, the transmit endadjusts the transmission parameter of the current data packet. x is apositive integer, and x≥2.

In some embodiments, x may be 2, 3, or 4. In other words, when theobtained transmission statuses of the previous two, three, or four datapackets of the first access stratum entity are transmission failure, thetransmit end adjusts the transmission parameter of the current datapacket. To be specific, when x=2, when transmitting a data packet whosesequence number is PDCP PDU #i, the first access stratum entity of thetransmit end determines transmission statuses of two previous datapackets, namely, data packets whose sequence numbers are PDCP PDU #(i-1)and PDCP PDU #(i-2). If the transmission statuses of the data packetswith the two sequence numbers are both transmission failure, thetransmit end adjusts a transmission parameter of the data packet withthe PDCP PDU #i. Cases for x=3 or x=4 is similar to the case for x=2,and details are not described herein again.

Maintenance of a Transmission Status and Adjustment of a TransmissionParameter Based on an RLC SDU Fed Back by the RLC Layer of a Receive End

FIG. 7 is a schematic flowchart of adjustment performed based on an RLCSDU transmission status error fed back by the RLC layer of a receive endaccording to an embodiment of this disclosure. The following uses anexample in which the receive end is an access network device, andincludes the following steps (but this disclosure is not limitedthereto).

Step S701: In some embodiments, in a process of establishing a radiobearer, the access network device determines, based on quality ofservice (QoS) information corresponding to the bearer, whether there isa requirement for transmission reliability of consecutive data packets.If there is a requirement for transmission reliability of consecutivedata packets, two sets of resource parameters are configured. The twosets of resource parameters are different at least in content of aRadioResourceConfigDedicated information element. The resource parametermay be specifically a maximum quantity of transmissions of a HARQ, amaximum quantity of transmissions of an ARQ, an MCS, or the like.However, this disclosure is not limited thereto. The QoS information maybe obtained from a core network, or may be obtained from a terminaldevice. In the following steps, State_RLC_1 is a variable used by atransmit end to maintain a transmission status of a previous datapacket, and State_RLC_2 is a variable used by the transmit end tomaintain a transmission status of a current data packet.

Step S702: An RLC entity of the terminal device receives an RLC SDU 1from an upper layer (for example, a PDCP layer), and sets a transmissionstatus variable State_RLC_1 corresponding to the RLC SDU 1 to False.

Step S703: It is assumed that the RLC SDU 1 is segmented fortransmission due to limited scheduling resources at a bottom layer, andis encapsulated into an RLC PDU 1 and an RLC PDU 2. A polling field inan RLC header of the RLC PDU 2 is set.

Step S704: It is assumed that the RLC PDU 1 fails to be transmitted, andthe RLC PDU 2 is transmitted successfully. When an RLC entity of theaccess network device receives the RLC PDU 2, because the polling fieldis set, the RLC entity of the access network device generates a statusreport, including information about whether each RLC PDU (including atleast the RLC PDU 1 and the RLC PDU 2) is successfully received.

Step S705: The terminal device receives the status report sent by theaccess network device, learns of transmission failure of the RLC PDU 1,determines that the RLC SDU 1 fails to be transmitted, and maintainsState_RLC_1 as False.

In some embodiments, the RLC layer indicates, to another protocol layersuch as an RRC layer, a MAC layer, a PHY layer, or a PDCP layer, thatthe transmission status of the RLC SDU 1 is failure. After receiving theindication, each protocol layer sets a transmission parametercorresponding to the protocol layer to a second resource parameter.

Step S706: The RLC entity of the terminal device receives the RLC SDU 2.Because State_RLC_1 is False, the second resource parameter is used totransmit the RLC SDU 2. The initial transmission status variableState_RLC_2 corresponding to the RLC SDU 2 is set to False.

Step S707: It is assumed that the RLC SDU 2 is not segmented at the RLClayer, the RLC SDU 2 is directly encapsulated into an RLC PDU 3, and theRLC PDU 3 is delivered to the bottom layer for transmission, where thepolling field is set.

Step S708: It is assumed the RLC PDU 3 is transmitted successfully, whenreceiving the RLC PDU 3, the RLC entity of the access network devicegenerates a status report because the polling field is set, where thestatus report includes information about whether each RLC PDU (includingat least the RLC PDU 3) is successfully received.

Step S709: The terminal device receives the status report sent by theaccess network device, learns that the RLC PDU 3 is transmittedsuccessfully, determines that the RLC SDU 2 is transmitted successfully,and sets State_RLC_2 to True.

In some embodiments, the RLC layer indicates, to another protocol layersuch as the RRC layer, the MAC layer, the PHY layer, or the PDCP layer,that the transmission status of the RLC SDU 2 is success. Afterreceiving the indication, each protocol layer sets a transmissionparameter corresponding to the protocol layer to a first resourceparameter.

Maintenance of a Transmission Status and Adjustment of a TransmissionParameter Based on an RLC SDU Fed Back by a MAC Layer of a Receive End

FIG. 8 is a schematic flowchart of adjustment performed based on an RLCSDU transmission status error fed back by the MAC layer of the receiveend according to an embodiment of this disclosure. The following uses anexample in which the receive end is an access network device, andincludes the following steps (but this disclosure is not limitedthereto).

Step 801 and step 802 are the same as step 701 and step 702 in FIG. 7,and details are not described herein again.

Step 803: It is assumed that the RLC SDU 1 is not segmented, the RLC SDU1 is encapsulated into an RLC PDU 1. The RLC PDU 1 is delivered to theMAC layer for transmission. The RLC PDU 1 is encapsulated into a MAC PDU1 at the MAC layer.

Step 804: It is assumed that the MAC PDU 1 fails to be transmitted for xconsecutive times, where x is a positive integer, the MAC layerindicates the information to an RLC entity where the RLC PDU 1 islocated. The RLC entity determines that the RLC SDU 1 fails to betransmitted, and maintains State_RLC_1 as False.

In some embodiments, x may be a maximum quantity of transmissions of aHARQ. The MAC layer indicates transmission failure of the RLC PDU 1 toan RLC layer after the maximum quantity of transmissions of the HARQ ofthe MAC PDU 1 is reached.

In some embodiments, the RLC layer indicate, to another protocol layersuch as an RRC layer, a MAC layer, a PHY layer, or a PDCP layer, thatthe transmission status of the RLC SDU 1 is failure. After receiving theindication, each protocol layer sets a transmission parametercorresponding to the protocol layer to a second resource parameter.

Step 805: The RLC entity of the terminal device receives an RLC SDU 2from an upper layer, and sets a transmission status variable State_RLC_2corresponding to the RLC SDU 2 to False.

Step 806: It is assumed that the RLC SDU 2 is not segmented, the RLC SDU2 is encapsulated into an RLC PDU 2. The RLC PDU 2 is delivered to theMAC layer for transmission. The RLC PDU 2 is encapsulated into a MAC PDU2 at the MAC layer.

Step 807: It is assumed that the MAC PDU 2 is transmitted successfully,the MAC layer indicates the information to an RLC entity in which theRLC PDU 2 is located, and the RLC entity determines that the RLC SDU 2is transmitted successfully, and maintains State_RLC_2 as True.

In some embodiments, the RLC layer indicates, to another protocol layersuch as the RRC layer, the MAC layer, the PHY layer, or the PDCP layer,that the transmission status of the RLC SDU 2 is success. Afterreceiving the indication, each protocol layer sets a transmissionparameter corresponding to the protocol layer to a first resourceparameter.

In some embodiments, in addition to the foregoing method for indicatinga transmission status of an RLC SDU, another indication method isfurther included. An example is as follows.

Each RLC entity of a transmit end (where a terminal device is used as anexample for uplink) maintains a transmission status of each RLC SDU inthe entity. For example, the RLC entity maintains a variableState_RLC_SN for an RLC SDU whose RLC layer sequence number is an SN.

In some embodiments, in Embodiment 1 and Embodiment 2, a condition forsetting the variable State_RLC_SN to False includes at least one of thefollowing:

(1) The variable State_RLC_SN is initially set to False. For example,the RLC SDU corresponding to the SN is obtained from the PDCP layer, orthe first RLC PDU corresponding to the RLC SDU is delivered to the MAClayer.

(2) Statuses received from a peer RLC entity indicate that at least oneof all RLC PDUs corresponding to the RLC SDU fails to be received.

In some embodiments, the RLC entity of the transmit end sets the pollingfield based on a quantity (for example, 1) of sent RLC SDUs, that is,sets the polling field when sending a last RLC PDU corresponding to eachRLC SDU, and the RLC entity of the receive end generates a status reporteach time receiving an RLC SDU.

(3) The MAC layer indicates that at least one of one or more MAC PDUs inwhich all RLC PDUs corresponding to the RLC SDU are located is nottransmitted successfully in n consecutive HARQ transmissions, where n isa positive integer and is configured by using RRC signaling of theaccess network device. In some embodiments, n may be equal to a maximumquantity of transmissions of a HARQ.

(4) The PDCP layer indicates that the RLC SDU or a PDCP SDU/PDUcorresponding to the RLC SDU is not transmitted successfully.

(5) The RLC layer does not receive, within a time range specified by atimer, a status report including transmission success of the RLC SDUcorresponding to the SN.

(6) That a value of State_RLC_SN is False is obtained directly fromsignaling (RLC control PDU, RRC signaling, MAC CE, or DCI) of a layer ofthe receive end. When failing to decode, at the RLC layer, an RLC SDUcorresponding to an SN (for example, because a reordering timer expiresor content of the SDU cannot be identified), the terminal devicegenerates signaling including that the value of State_RLC_SN is False.The signaling may be RRC signaling, a MAC control element (CE), an RLCcontrol PDU, or downlink control information (DCI).

In some embodiments, in Embodiment 1 and Embodiment 2, a condition forsetting the variable State_RLC_SN to True includes at least one of thefollowing:

(1) A status report fed back by a peer RLC entity indicates that RLCPDUs corresponding to the RLC SDU are all successfully received. In someembodiments, the RLC entity of the transmit end sets the polling fieldbased on a quantity (for example, 1) of sent RLC SDUs, that is, sets thepolling field when sending a last RLC PDU corresponding to each RLC SDU.

(2) The MAC layer indicates that MAC PDUs in which RLC PDUscorresponding to the RLC SDU are located are all transmittedsuccessfully, and the MAC layer feeds back, to an RLC entitycorresponding to each logical channel, a transmission status of each RLCPDU of the RLC entity.

(3) The PDCP layer indicates that the RLC SDU or a PDCP SDU/PDUcorresponding to the RLC SDU is transmitted successful.

(4) That a value of State_RLC_SN is True is obtained directly fromsignaling (PDCP control PDCU, RLC control PDU, MAC CE, DCI, or RRCsignaling) of a layer of the receive end.

When successfully decoding an RLC SDU corresponding to an SN at the RLClayer, the receive end generates signaling including that the value ofState_RLC_SN is True. The signaling may be RRC signaling, a MAC CE, anRLC control PDU, or DCI.

In some embodiments, the RLC entity indicates a transmission status ofeach RLC SDU to another layer, for example, the RRC layer, the SDAPlayer, the PDCP layer, the MAC layer, or the PHY layer.

When the value of State_RLC_SN is False, if an RLC SDU whose sequencenumber is an SN+1 is sent, the transmit end performs transmission byusing the second resource parameter. This includes the following steps:

(1) The PDCP layer or the RLC layer activates duplication of a bearer ora logical channel on which the RLC SDU with the SN+1 is located.

(2) The RLC SDU with the SN+1 is transmitted based on a pre-configuredparameter (for example, a quantity of transmission time intervalbundling (TTI bundling), a modulation and coding scheme, a maximumquantity of transmissions of a hybrid automatic repeat request HARQ, amaximum quantity of transmissions of an automatic repeat request ARQ, aperiod of a transmission resource, a location of a transmissionresource, a size of a transmission resource, a type of a transmissionresource, a priority of a logical channel, a priority of a radio bearer,a transmission mode of radio link control, a quantity of transmittedcarriers, a type of a radio bearer, a function of a radio bearer, or thelike). The parameter is configured by using RRC signaling and activatedwhen the RLC SDU whose sequence number is the SN fails to betransmitted.

Similar to FIG. 7, FIG. 9 is a schematic flowchart of adjustmentperformed based on a PDCP SDU transmission status error fed back by aPDCP layer of a receive end according to an embodiment of thisdisclosure. Each PDCP entity of a transmit end (where a terminal deviceis used as an example for uplink) maintains a transmission status ofeach PDCP SDU/PDU in the entity. For example, the PDCP entity maintainsa variable State_PDCP_SN for a PDCP SDU/PDU whose PDCP layer sequencenumber is an SN.

In some embodiments, a condition for setting the variable State_PDCP_SNto False includes at least one of the following:

(1) The variable State_PDCP_SN is initially set to False. For example, aPDCP SDU is obtained from an upper layer (an SDAP layer, an IP layer, oran application layer), or a PDCP PDU (whose sequence number is the SN)corresponding to the PDCP SDU is delivered to an RLC layer.

(2) A status report received from a peer PDCP entity indicates the PDCPSDU/PDU fails to be transmitted. A PDCP entity of the transmit end setsa polling field in a header of each PDCP PDU, and the PDCP entity of thereceive end generates a status report each time receiving a PDCP PDU.

(3) The RLC layer indicates transmission failure of a current PDCP PDUat the PDCP layer.

(4) A discardTimer of the PDCP layer for the PDCP SDU expires.

(5) That a value of State_PDCP_SN is False is obtained directly fromsignaling (PDCP control PDU, RRC signaling, MAC CE, or DCI) of a layerof a peer end.

(6) Anon-access stratum (NAS), an application layer, or an IP layerprovides an indication.

In some embodiments, a condition for setting the variable State_PDCP_SNto True includes at least one of the following:

(1) A status report fed back by a PDCP entity of the receive endindicates that the PDCP SDU/PDU is transmitted successfully.

(2) The RLC layer indicates that the PDCP SDU/PDU is transmittedsuccessfully.

(3) That a value of State_PDCP_SN is True is obtained directly fromsignaling (PDCP control PDU, MAC CE, DCI, or RRC signaling) of a layerof the peer end. When successfully decoding a PDCP SDU corresponding toan SN at the PDCP layer, the receive end generates signaling includingthat the value of State_PDCP_SN is True. The signaling may be RRCsignaling, a MAC CE, a PDCP control PDU, or DCI.

(4) A NAS layer, an application layer, or an IP layer providesindication information.

In some embodiments, the PDCP entity indicates a transmission status ofeach PDCP SDU/PDU to another layer, for example, the RRC layer, the SDAPlayer, the RLC layer, the MAC layer, or the PHY layer.

Similarly, when the value of State_PDCP_SN is False, if a PDCP SDU whosesequence number is an SN+1 is sent, the transmit end performstransmission by using the second resource parameter. This includes thefollowing steps:

(1) The PDCP layer or the RLC layer activates duplication (duplication)of bearers or logical channels on which the PDCP SDU with the SN+1 islocated.

(2) The PDCP SDU with the SN+1 is transmitted based on a pre-configuredparameter (which may include: a quantity of TTI bundling, a modulationand coding scheme, a maximum quantity of transmissions of a hybridautomatic repeat request HARQ, a maximum quantity of transmissions of anautomatic repeat request ARQ, a period of a transmission resource, alocation of a transmission resource, a size of a transmission resource,a type of a transmission resource, a priority of a logical channel, apriority of a radio bearer, a transmission mode of radio link control, aquantity of transmitted carriers, a type of a radio bearer, a functionof a radio bearer, or the like). The parameter is configured by usingRRC signaling and activated when the PDCP SDU whose sequence number isthe SN fails to be transmitted.

FIG. 10 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to an embodiment ofthis disclosure. That a transmit end is an access network device is usedas an example. The method specifically includes the following steps.

Step 1001: The access network device obtains a period of a data packetfrom a core network device. The access network device should receive adata packet in each period.

Step 1002: The access network device receives a data packet 1 in aperiod 1, and transmits the data packet 1 based on a transmissionparameter 1 (a first resource parameter). It is assumed that the datapacket 1 is transmitted successfully on an air interface.

Step 1003: The access network device sends the data packet 1 to aterminal device.

Step 1004: The core network device sends a data packet 2 to the accessnetwork device, but the access network device does not receive the datapacket 2 in a period 2. In this case, the data packet 2 of the accessnetwork device fails to be transmitted (that is, the data packet 2 islost).

Step 1005: The access network device sets a transmission status of thedata packet 2 to transmission failure, and adjusts a transmissionparameter of a data packet 3 to a transmission parameter 2 (a secondresource parameter).

Step 1006: The access network device receives, in a period 3, the datapacket 3 sent by the core network device.

Step 1007: The access network device sends the data packet 3 to theterminal device.

FIG. 11 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to an embodiment ofthis disclosure. That a transmit end is a terminal device is used as anexample. The method specifically includes the following steps.

Step 1101: A PDCP layer of the terminal device sends a PDCP SDU 1 to anaccess network device.

Step 1102: The terminal device obtains, from a NAS layer or anapplication layer, an indication that the PDCP SDU 1 is transmittedincorrectly, and the terminal device sets a transmission statuscorresponding to the PDCP SDU 1 to transmission error. The terminaldevice adjusts a transmission parameter of a PDCP SDU 2 to atransmission parameter 2 (a second resource parameter), to transmit thePDCP SDU 2.

Step 1103: The terminal device transmits the PDCP SDU 2 to the accessnetwork device by using the transmission parameter 2.

FIG. 12 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to an embodiment ofthis disclosure. That a transmit end is a terminal device is used as anexample. The method specifically includes the following steps.

Step 1201: A PDCP layer of the terminal device sends a PDCP SDU 1 to anaccess network device, and simultaneously starts a timer.

Step 1202: The terminal device does not obtain indication information oftransmission success of the PDCP SDU 1 before the timer expires. Theterminal device sets a transmission status corresponding to the PDCP SDU1 to transmission error, and adjusts a transmission parameter of a PDCPSDU 2 to a transmission parameter 2 (a second resource parameter), totransmit the PDCP SDU 2.

Step 1203: The terminal device transmits the PDCP SDU 2 to the accessnetwork device by using the transmission parameter 2.

FIG. 13 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to an embodiment ofthis disclosure. That a transmit end is an access network device is usedas an example. The method specifically includes the following steps.

Step 1301: The access network device successfully receives a data packet1 sent by a core network device.

Step 1302: The access network device sends the data packet 1 to aterminal device.

Step 1303: The access network device successfully receives a data packet3 sent by the core network device. The access network device finds thata data packet 2 is missing, indicating that the data packet 2 is lost orfails to be transmitted.

Step 1304: The access network device sets a transmission status of thedata packet 2 to transmission failure, and adjusts a transmissionparameter of the data packet 3 to a transmission parameter 2 (a secondresource parameter).

Step 1305: The access network device sends the data packet 3 to theterminal device based on the transmission parameter 2.

FIG. 14 is a schematic flowchart of another method for avoiding failureof transmitting consecutive data packets according to an embodiment ofthis disclosure. That a transmit end is a terminal device is used as anexample. The method specifically includes the following steps.

Step 1401: A PDCP layer of the terminal device sends a PDCP SDU 1 to anaccess network device.

Step 1402: The access network device notifies, by using DCI or a MAC CE,the terminal device that a transmission status of the PDCP SDU 1 istransmission failure. Alternatively, the access network device instructsthe terminal device to transmit a next PDCP SDU, namely, a PDCP SDU 2,by using a second resource parameter (not shown in the figure).

Step 1403: The terminal device sets the transmission statuscorresponding to the PDCP SDU 1 to transmission failure, and adjusts atransmission parameter of the PDCP SDU 2 to a transmission parameter 2(the second resource parameter), to transmit the PDCP SDU 2.

Step 1404: The terminal device transmits the PDCP SDU 2 to the accessnetwork device by using the transmission parameter 2.

It should be noted that all entities in the embodiments of thisdisclosure may be replaced with other entities, and the SDU may be aPDU. This is not limited in this disclosure. In the method provided inthe embodiments of this disclosure, the transmission parameter of thecurrent data packet is adjusted based on that the transmission status ofthe previous data packet is transmission error. When the transmissionstatus of the previous data packet is a correct transmission, thetransmit end does not adjust the transmission parameter of the currentdata packet.

According to the method in the embodiments of this disclosure, atransmission policy of a next data packet can be quickly adjusted basedon a transmission status of a previous data packet, and higherreliability is used to ensure transmission of the next data packet whenthe previous data packet fails to be transmitted. This avoids failure oftransmitting two consecutive data packets.

An example of this disclosure further provides an apparatus (forexample, an integrated circuit, a wireless device, or a circuit module),configured to implement the foregoing method. The apparatus for avoidingfailure of transmitting consecutive data packets described in thisspecification may be an independent device or may be a part of a largerdevice. The device may be: (i) an independent IC, (ii) a set of one ormore ICs, where the set may include a memory IC configured to store dataand/or an instruction, (iii) an RFIC such as an RF receiver or an RFtransmitter/receiver, (iv) an ASIC such as a mobile station modem, (v) amodule that can be embedded in another device, (vi) a receiver, acellular phone, a wireless device, a hand-held phone, or a mobile unit,or (vii) others.

The method and apparatus that are provided in the embodiments of thisdisclosure may be applied to the terminal device or the access networkdevice (which may be collectively referred to as a wireless device). Theterminal device, the access network device, or the wireless device mayinclude a hardware layer, an operating system layer running on thehardware layer, and an application layer running on the operating systemlayer. The hardware layer includes hardware such as a central processingunit (CPU), a memory management unit (MMU), and an internal memory (alsoreferred to as a main memory). The operating system may be any one ormore types of computer operating systems, for example, a Linux operatingsystem, a Unix operating system, an Android operating system, an iOSoperating system, and a Windows operating system, that implement serviceprocessing by using a process. The application layer includesapplications such as a browser, an address book, word processingsoftware, and instant messaging software. In addition, in theembodiments of this disclosure, a specific structure of an executionbody of the method is not limited in the embodiments of this disclosure,provided that a program that records code of the method in theembodiments of this disclosure can be run to perform communicationaccording to the signal transmission method in the embodiment of thisdisclosure. For example, the method for avoiding failure of transmittingconsecutive data packets in the embodiments of this disclosure may beperformed by a terminal device or an access network device, or may beperformed by a function module that can invoke a program and execute theprogram in the terminal device or the access network device.

A person of ordinary skill in the art may be aware that, in combinationwith the units and algorithm steps in the examples described in theembodiments disclosed in this specification, this disclosure may beimplemented by electronic hardware or a combination of electronichardware and computer software. Whether the functions are performed byhardware or software depends on particular applications and designconstraint conditions of the technical solutions. A person skilled inthe art may use different methods to implement the described functionsfor each particular application, but it should not be considered thatthe implementation goes beyond the scope of the embodiments of thisdisclosure.

In addition, aspects or features of the embodiments of this disclosuremay be implemented as a method, an apparatus or a product that usesstandard programming and/or engineering technologies. The term “product”used in this disclosure covers a computer program that can be accessedfrom any computer-readable component, carrier, or medium. For example,the computer-readable medium may include but is not limited to: amagnetic storage component (for example, a hard disk, a floppy disk, ora magnetic tape), an optical disc (for example, a compact disc (CD), adigital versatile disc (DVD), a smart card, and a flash memory component(for example, an erasable programmable read-only memory (EPROM), a card,a stick, or a key drive). In addition, various storage media describedin this specification may indicate one or more devices and/or othermachine-readable media that are configured to store information. Theterm “machine-readable media” may include but is not limited to a radiochannel and other various media that can store, contain, and/or carry aninstruction and/or data.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, the embodiments may be implementedcompletely or partially in a form of a computer program product. Thecomputer program product includes one or more computer programinstructions. When the computer program instruction is loaded andexecuted on a computer, the procedure or functions according to theembodiments of the present application are all or partially generated.The computer may be a general-purpose computer, a dedicated computer, acomputer network, or another programmable apparatus. The computerinstruction may be stored in a computer-readable storage medium or maybe transmitted from a computer-readable storage medium to anothercomputer-readable storage medium. For example, the computer instructionmay be transmitted from a website, computer, server, or data center toanother website, computer, server, or data center in a wired (forexample, a coaxial cable, an optical fiber, or a digital subscriber line(DSL)) or wireless (for example, infrared, radio, and microwave, or thelike) manner. The computer-readable storage medium may be any usablemedium accessible by the computer, or a data storage device, such as aserver or a data center, integrating one or more usable media. Theusable medium may be a magnetic medium (for example, a floppy disk, ahard disk, or a magnetic tape), an optical medium (for example, a DVD),a semiconductor medium (for example, a solid-state drive (SSD)), or thelike.

It should be understood that sequence numbers of the foregoing processesdo not mean execution sequences in various embodiments of thisdisclosure. The execution sequences of the processes should bedetermined based on functions and internal logic of the processes, andshould not be construed as any limitation on the implementationprocesses of the embodiments of this disclosure.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiments, and detailsare not described herein again.

In the several embodiments provided in this disclosure, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiments are merely examples. For example, division into the modulesor units is merely logical function division and may be other divisionduring actual implementation. For example, a plurality of units orcomponents may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual couplings or direct couplings or communicationconnections may be implemented by using some interfaces. The indirectcouplings or communication connections between the apparatuses or unitsmay be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

When the functions are implemented in the form of a software functionunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of this disclosure essentially,or the part contributing to some approaches, or some of the technicalsolutions may be implemented in a form of a software product. Thesoftware product is stored in a storage medium, and includes severalinstructions for instructing a computer device (which may be a personalcomputer, a server, a network device, or the like) to perform all orsome of the steps of the methods described in the embodiments of thisdisclosure. The foregoing storage medium includes any medium that canstore program code, for example, a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific implementations of thisdisclosure, but are not intended to limit the protection scope of thisdisclosure. Any variation or replacement readily figured out by a personskilled in the art within the technical scope disclosed in thisdisclosure shall fall within the protection scope of the embodiments ofthis disclosure.

What is claimed is:
 1. An apparatus, comprising: a processor; and anon-transitory computer-readable storage medium coupled to theprocessor, and configured to store programmable instructions, inresponse to execution by the processor, the programmable instructionscause the apparatus to: maintain transmission statuses of previous ndata packets of a first access stratum entity and that are countedbackwards; and adjust a transmission parameter of a current data packet,in response to n consecutive data packets having obtained thetransmission statuses that correspond to transmission failures, whereinn is an integer, n≥2, and a transmission status of a previous datapacket corresponds to a transmission failure in response to a timer,maintained by the first access stratum entity of the apparatus, expiringand the previous data packet not being transmitted successfully.
 2. Theapparatus according to claim 1, wherein the first access stratum entityincludes at least: a radio link control layer; a service data adaptationprotocol layer; a radio resource control layer; a media access controllayer, or a physical layer.
 3. The apparatus according to claim 1,wherein the current data packet is a service data unit or a protocoldata unit.
 4. The apparatus according to claim 1, wherein theprogrammable instructions that cause the apparatus to maintain thetransmission status of the previous data packet of the first accessstratum entity is further based on the transmission status of theprevious data packet corresponding to a transmission success in responseto the previous data packet being transmitted successfully before thetimer, maintained by the first access stratum entity expires.
 5. Theapparatus according to claim 1, wherein the programmable instructionsthat cause the apparatus to maintain the transmission status of theprevious data packet of the first access stratum entity is based on:indication information from the first access stratum entity of a receiveend to an access stratum entity of the apparatus indicates that theprevious data packet of the first access stratum entity of the apparatusis transmitted successfully or fails to be transmitted.
 6. The apparatusaccording to claim 1, wherein the programmable instructions that causethe apparatus to maintain the transmission status of the previous datapacket of the first access stratum entity is based on: indicationinformation from a second access stratum entity of the apparatus to thefirst access stratum entity of the apparatus indicates that the previousdata packet of the first access stratum entity of the apparatus istransmitted successfully or fails to be transmitted.
 7. The apparatusaccording to claim 1, wherein the programmable instructions that causethe apparatus to maintain the transmission status of the previous datapacket of the first access stratum entity is based on: indicationinformation from a second access stratum entity of a receive end to thefirst access stratum entity of the apparatus indicates that the previousdata packet of the first access stratum entity of the apparatus istransmitted successfully or fails to be transmitted.
 8. The apparatusaccording to claim 1, wherein the programmable instructions that causethe apparatus to maintain the transmission status of the previous datapacket of the first access stratum entity is based on: indicationinformation from the first access stratum entity or a second accessstratum entity of the apparatus to the first access stratum entity ofthe apparatus, the indication information determines, based on sequencenumbers of corresponding data packets, that the previous data packetfail to be transmitted in response to a sequence number of the receivedcurrent data packet and a sequence number of the previous data packetare not consecutive.
 9. The apparatus according to claim 1, wherein theprogrammable instructions that cause the apparatus to maintain thetransmission status of the previous data packet of the first accessstratum entity is based on: indication information from a second accessstratum entity of the apparatus to the first access stratum entity ofthe transmit end, the indication information is useable to learn of aperiod of a data packet based on quality of service (QoS) information,and the indication information is useable to determine that the previousdata packet failed to be transmitted in response to no data packet beingreceived within a previous period.
 10. The apparatus according to claim1, wherein the programmable instructions that cause the apparatus tomaintain the transmission status of the previous data packet of thefirst access stratum entity is based on: indication information from anon-access stratum entity or an application layer of the apparatus tothe first access stratum entity of the apparatus, the indicationinformation indicates that the previous data packet of the first accessstratum entity of the apparatus is transmitted successfully or fails tobe transmitted.
 11. The apparatus according to claim 1, wherein thetransmission parameter includes at least: a modulation and codingscheme; a maximum quantity of transmissions of a hybrid automatic repeatrequest (HARQ); a maximum quantity of transmissions of an automaticrepeat request (ARQ); a period of a transmission resource; a location ofthe transmission resource; a size of the transmission resource; a typeof the transmission resource; a priority of a logical channel; apriority of a radio bearer; a transmission mode of radio link control; aquantity of transmitted carriers; a type of the radio bearer; a functionof the radio bearer; or a transmission power.
 12. An apparatus,comprising: a processor; and a non-transitory computer-readable storagemedium coupled to the processor, and configured to store programmableinstructions, when executed by the processor, the programmableinstructions cause the apparatus to: obtain transmission statuses ofprevious n data packets of a first access stratum entity and that arecounted backwards; and adjust a transmission parameter of a current datapacket, in response to m data packets in the previous n data packets,the m data packets having obtained transmission statuses that correspondto transmission failures, wherein m and n are positive integers, andm≤n, wherein a transmission status of the transmission statuses of aprevious data packet of the previous n data packets corresponds to atransmission failure in response to a timer, maintained by the firstaccess stratum entity, expiring and the previous data packet of theprevious n data packets not being transmitted successfully.
 13. Theapparatus according to claim 12, wherein the programmable instructionsthat cause the apparatus to obtain the transmission statuses of theprevious n data packets of the first access stratum entity is based on:m data packets in the previous n data packets have a correspondingtransmission status as transmission failure in response to a quantity ofdata packets that fail to be transmitted is greater than or equal to m,the quantity of data packets that fail to be transmitted being countedby a counter maintained by the first access stratum entity of theapparatus.
 14. The apparatus according to claim 12, wherein theprogrammable instructions that cause the apparatus to obtain thetransmission statuses of the previous n data packets of the first accessstratum entity is based on: indication information from the first accessstratum entity of a receive end to an access stratum entity of atransmit end indicates whether there are m data packets that fail to betransmitted in the previous n data packets of the first access stratumentity of the receive end.
 15. The apparatus according to claim 12,wherein the programmable instructions that cause the apparatus to obtainthe transmission statuses of the previous n data packets of the firstaccess stratum entity is based on: indication information from a secondaccess stratum entity of the apparatus to the first access stratumentity of a transmit end indicates whether there are m data packets thatfail to be transmitted in the previous n data packets of the firstaccess stratum entity of the transmit end.
 16. The apparatus accordingto claim 12, wherein the programmable instructions that cause theapparatus to obtain the transmission statuses of the previous n datapackets of the first access stratum entity is based on: indicationinformation from a second access stratum entity of a receive end to anaccess stratum entity of a transmit end indicates whether there are mdata packets that fail to be transmitted in the previous n data packetsof the first access stratum entity of the transmit end.
 17. Theapparatus according to claim 12, wherein the programmable instructionsthat cause the apparatus to obtain the transmission statuses of theprevious n data packets of the first access stratum entity is based on:indication information from a non-access stratum entity or anapplication layer of a transmit end to the first access stratum entityof the transmit end, the indication information indicates whether thereare m data packets that fail to be transmitted in the previous n datapackets of the first access stratum entity of the transmit end.
 18. Theapparatus according to claim 12, wherein n is configured by an accessnetwork device or a core network device, or n is obtained from anapplication layer or a non-access stratum entity of a terminal device.19. An apparatus, comprising: a processor; and a non-transitorycomputer-readable storage medium coupled to the processor, andconfigured to store programmable instructions, in response to executionby the processor, the programmable instructions cause the apparatus to:obtain transmission statuses of at least k data packets that are of afirst access stratum entity and that are counted backwards; and adjust atransmission parameter of a current data packet in response to kconsecutive data packets having obtained transmission statuses thatcorrespond to transmission failures and are part of the first accessstratum entity, wherein k is a positive integer, and k≥2.
 20. Anapparatus, comprising: a processor; and a non-transitorycomputer-readable storage medium coupled to the processor, andconfigured to store programmable instructions, in response to executionby the processor, the programmable instructions cause the apparatus to:obtain transmission statuses of at least previous x data packets of afirst access stratum entity and that are counted backwards; and adjust atransmission parameter of a current data packet, in response to thetransmission statuses of the previous x data packets being transmissionfailures, wherein x is a positive integer, and x≥2, wherein atransmission status of the transmission statuses of a previous datapacket of the previous x data packets corresponds to a transmissionfailure in response to a timer, maintained by the first access stratumentity, expiring and the previous data packet of the previous x datapackets not being transmitted successfully.